Recently, in order to overcome the far-field diffraction limitation, the near-field scanning optical microscopy (NSOM) has been disclosed in U.S. Pat. No. 4,917,462, U.S. Pat. No. 5,894,122, U.S. Pat. No. 5,994,691, and U.S. Pat. No. 6,194,711, wherein NSOM is designed so that a probe whose aperture or radius of curvature of the tip is smaller than the wavelength of light used for measurement is placed close to the surface of a specimen, which is scanned with the probe to measure optical properties in a minute area of the specimen. NSOM is not restricted by the diffraction limit. For NSOM, while in a scattering probe, the resolving power corresponds to the order of the radius of curvature of the probe tip, and to the size of the outside diameter of the probe tip.
Due to the precise feedback control for the scanning system, the scanning velocity is slow, the scanning range is limited and the probe is easily destroyed. In order to overcome the aforesaid drawbacks and commercialize the near-field optical recording products, in U.S. Pat. No. 6,226,258, U.S. Pat. No. 6,319,582 and U.S. Pat. No. 6,340,813 in 2001 and in 2002, Junji Tominaga et al disclosed a design for increasing two nano-films, i.e. the SiN layer with a thickness of 20 nm and the Sb layer with a thickness of 15 nm, on the phase-change typed optical recording media, wherein the two nano-films played a role as the probe in the near-field microscopes to read and write the recording points smaller than the diffraction limitation. In addition, U.S. Pat. No. 6,348,251, U.S. Pat. No. 6,358,589, US patent publication No. 20030211336, US patent publication No. 20030218969, US patent publication No. 20030218970, and US patent publication No. 20030032822 also disclosed the associated the near-field optical recording medium performing the surface plasmon effects. However, the aforesaid technologies are used for the near-field application. Accordingly, the present invention provides a component and a method to overcome the far-field diffraction limitation.
There are many studies about the materials and the structures for enhancing the surface plasmon resonance. The metal has a dielectric material soldered thereon, and the dielectric constant of the dielectric material is changed when the light is coupled to the surface of the metal. Alternatively, the different incident angles are selected and the corresponding reflected light signals are measured, so that the maximal surface plasmon resonance energy is obtained. The foregoing conventional technology is broadly used for the biomedical detections and the measurements of the dielectric constants.
Based on the principle of the surface plasmon resonance, the present invention provides a component having a surface plasmon polariton structure for enhancing the light beam transmission to the far-field and changing the distribution of the light field, so as to overcome the diffraction limitation.
T. W. Ebbesen disclosed the light signal enhancement from the subwavelength aperture array, in which it was proved that the light signal is passively enhanced due to the surface plasmon polariton (SPP) phenomenon formed by the nano-structure. In U.S. Pat. No. 6,236,033, the nano-aperture and the periodic structure formed on the metal film have been disclosed for enhancing the light transmission with the specific wavelength by using the characteristics of the surface plasmon polariton. In U.S. Pat. No. 6,052,238, the near-field scanning optical microscope having a subwavelength aperture array has been disclosed to enhance light transmission. For a single nano-aperture with the periodic structure, not only the single-surface structure but also the two-surfaces structure are used for enhancing the light signal, so that the photon entanglement can be preserved or lost upon transmission through the aperture.
The present invention provides a light-enhancing component having a surface plasmon polariton structure, and provides a method for fabricating the light-enhancing component by using the focused-ion-beam.